You completely missed my comments about the power windows. The fuel pump had better not be running when you're not cranking the engine. If it does, that creates a serious fire hazard. Typically the pump will run for one or two seconds after you turn on the ignition switch to be sure pressure is up for starting, but then it will turn off again until the Engine Computer sees engine rotation, (cranking or running). At that point it will turn the fuel pump back on. The reason they do that is if a fuel line is ruptured in a crash, the pump would dump raw fuel on the ground creating a fire hazard. With no fuel pressure due to the broken fuel line, the engine can't run. When it stalls, no signals are received from the crankshaft position sensor and camshaft position sensor. The loss of those signals is what tells the computer the engine isn't rotating. In response, the computer turns the fuel pump, and other stuff, off. A lot of people get hung up on the first thing they find missing, the fuel pump in this case, but the most common causes of engine stalling also include loss of spark. You need to check for both things, not just the first one you find missing.
In your case you have the additional observation and clue of the inoperative power windows and seats. The first and easiest thing to look at is that fuse box connection I mentioned as that will affect everything you observed. The next suspect probably would be the ignition switch or the terminals in the connector to it. There's a lot of current going through there, especially when people use the heater fan on the higher settings a lot. It only takes a tiny amount of arcing or pitting on the switch contacts to cause heat buildup, and that leads to degraded connections that become discolored, and usually start to melt the connector body. If it gets that far and that's what you find, I'll describe the typical repair procedure.
We can't dismiss your comments about cleaning the fuses, but that very rarely solves anything. It's much more likely you have a simple intermittent problem that acts up at times and works properly at other times. This is where we have to be careful about what we count as clues. It's very likely the electrical circuit started working on its own, and whatever you were doing at the time got counted as a clue. Banging on the gas tank is a common way to get a Chrysler fuel pump going. When they fail, they fail to start up leaving you stranded in your driveway. GM pumps usually fail while you're driving, leaving you stranded alongside the highway. "USUALLY". But again, we have to include the window and seat problem.
If the windows stop working simply because you turned the ignition switch off, I shouldn't be using that as a clue. In fact, when that bad connection develops at the fuse box, the starter usually doesn't work either, and it sounds like yours is working fine.
The next time it doesn't start, don't bang on the tank or remove any fuses. The goal is to keep the problem acting up so it can be diagnosed. Check for spark then. If that's missing too, we have to look for what everything has in common.
Friday, September 19th, 2014 AT 12:41 AM